FI96319C - Gel composition to protect cables that lead to low direct current, from damage caused by moisture, and a method for preventing a short circuit and for making a cable using the composition - Google Patents

Abstract

A gel composition including a water absorbent polymer of a hydrocarbon chain backbone with pendent anionic groups. The gel composition is activated with moisture so that the water absorbent composition migrates to absorb the water. Also, the gel composition protects wires which carry a small dc current and heals shorts caused by moisture in such wires. The gel composition can include a tackifier which makes the mixture adhere to surfaces.

Description

96319

This invention relates to a chemical composition of gels. The present invention relates to a gel chemical composition for protecting a conductor of low DC conductors from moisture damage and to a method for preventing short circuits and making a cable using this composition. Moisture activates the gel composition to absorb water and can be used to protect components from water damage. The composition may be a gel or a gel with an adhesive added to make the gel sticky for coating and adhering to the surfaces.

The gel composition can be placed in confined areas, such as inside cable sheaths and joints, to protect communication cables for long periods of time. The gel can still be inserted into the sheath before or during the operation of the joints. The sticky gel can be used to coat the conductors and fill the internal spaces of the cables during cable manufacturing. In addition to protecting the 20 conductors, the composition also corrects short circuits in wires, such as low-current telephone lines.

Communication cables, such as telephone wires, consist of a large number of conductors, typically copper-conductors, insulated with a plastic sheath, paper sheath, or other materials. A multi-conductor cable is enclosed in a flexible cable shield. Typically, the conductors are coated with a thin layer of thermoplastic resin, such as polyethylene. 30 The conductors are drawn through a vessel containing heated thermoplastic resin, and as the conductor passes through the hot resin, a thin coating is deposited on the conductor which adheres as it cools. This process takes place before the wire is wound. When connecting the wound conductors to make a cable inside the cable shield, fillers, such as petroleum gel, are added to fill the gaps.

The extensions of the communication cables are placed inside a housing-type shield, which may contain one thousand to 5 separately connected conductors. The cable connections are protected by sheaths that enclose the cable connections. Diapers are usually kept under pressure. Diapers are placed underground or above ground. The shields are exposed to damaging conditions that can cause diaper-10 leaks and allow water to enter.

In use, the cable conductors are connected to one or more small DC power sources to provide the necessary electrical current and possibly to a telephone terminal, one or more telephone transmitters located at one end or location, and one or more telephone receivers located at the other end. Sheaths are pressure type shielding systems and it is critical to prevent the ingress of harmful water and to protect the joints from moisture. The ingress of moisture 20 into cable joints or inside a cable not surrounded by a shield will cause moisture to pass through the conductor from one conductor to another if the insulation of the cables is not maintained. When this happens, either the wires short circuit or crosstalk occurs, causing telephone connections to be lost.

One method of providing additional protection for internal joints within a sheath involves wrapping a bundle within a flexible material and injecting a liquid epoxy or urethane resin into the sheath, which liquid resin solidifies within the sheath. The composition must be mixed in situ and is typically injected into the sheath by gravity. The material does not usually fill the entire interior of the housing, but leaves a cavity. These cavities or channels can form a way for water to enter, especially inside the sheath and in the cable harness.

It 3 96319 forming a bundle at either end. As in the sheath, the sheath surrounding the joints can also cause a funnel effect such that water enters from one end of the shield around the cable and inside the sheath surrounding the bundle 5.

The present invention relates to a composition for protecting low-voltage conductive telecommunication or other cable conductors from damage due to moisture contact with defects or cracks in the conductor insulators. The composition according to the invention comprises a dielectric gel matrix and is characterized in that a polymer having a hydrocarbon backbone having anionic groups attached to it is dispersed in the gel matrix, the anionic group-containing polymer being exposed to a direct current from the damaged conductor which excludes water from the surface of the conductor, and wherein the composition is relatively non-conductive with respect to poor direct current.

The invention also relates to a method for preventing or correcting a short circuit in conductors of telecommunication and other cables conducting low direct current, which short circuit is due to moisture contact with defects or cracks in the cable insulation. For this method! 25 is characterized in that the above-described composition according to the invention is applied to the cable conductors.

The invention further relates to a method of manufacturing a telecommunication cable or a low direct current cable, in which the above composition of the invention is sprayed into a sheath or shield surrounding the conductors of the cable during the manufacture of the cable. The invention also relates to a telecommunication cable or a low direct current cable, the conductors of which are surrounded by a composition according to the invention.

4,96319

The composition according to the invention is thus an adhesive-containing or non-adhesive gel composition, which may be a cable filler, a conductor coating or a gel sprayed into the sheath or shield surrounding the conductors or joints, which acts to protect against harmful water. The gel can be placed inside the diaper during the manufacturing process or after the diaper is put into use.

The preferred composition consists of a water-absorbent polymer having a hydrocarbon chain as the backbone and having 10 free anionic groups attached to the polymer backbone, which polymer is mixed with a dielectric gel matrix. In many cases, the dielectric gel matrix is hydrophobic and the addition of a hydrophilic substance is necessary, as explained below.

15 The gel composition itself forms the first ve barrier. If water enters, the water-absorbing polymer is activated and the water is absorbed. In the tests, water was placed next to the gel composition. A fine powdery substance is observed to move towards water away from the gel matrix. The composition has shown this movement phenomenon up to 15 cm from the original gel matrix boundary. It turns out to be a water-absorbing polymer that targets water. Upon contact with water, it forms a gel-like material similar to a mixture of polymer and water. The addition of a hydrophilic substance to a gel matrix of hydrophobic materials appears to promote this movement towards water.

It has been found that when polymers with free anionic groups are exposed to a small direct current, such as a current in a telephone line, for example, it appears to cause the conductors acting as an anode to attract the polymer containing the anionic groups. This clear attraction of the unprotected conductor to the polymer brings the polymer into electrochemical contact with the conductor and creates an insulator that prevents water 5 96319 from entering the conductor surface. Insulation is formed and an electrical path through the conductor is provided with a short circuit eliminated. The polymer is typically in granular form. The composition of the present invention is a mixture of a polymer and other substances which forms a gel which is substantially non-direct current and which can be used in telecommunications. The Gee-melt matrix alloy does not reduce or prevent conductor insulation.

The gel composition plays many roles in protecting the contents of the housings or the components inside them from moisture damage. First, as moisture penetrates inside, the gel composition expels water. In the presence of moisture, the water-absorbing component of the gel is activated so that it migrates out of the gel matrix to absorb water. This is particularly practical when using cables with very small intermediate spaces in a large number of conductors. The composition travels to small spaces if moisture is present. This creates a blocking effect in terms of the penetration of additional water. This advantage is achieved regardless of whether electric current is present or not.

For example, in the case of damaged communication links with a low direct current, the polymer also repairs the short circuit by accumulating on the surface of the conductor as described above. The gel composition prevents water from entering and repairs the short circuit, keeping the current in the conductor-25. When any water enters the sheath and under the influence of a small direct current, the water-absorbing, insulating polymer in the matrix is activated to insulate the unprotected conductor.

The gel composition can be modified in terms of the viscosity taken and the tolerance to environmental conditions and can be placed inside a pressurized jacket. The viscosity of the non-adhesive gel can vary from 2 mm 2 / s (2 cSt) at 100 eC to 0.09 m 2 / s (90,000 cSt) at 40 eC. The viscosity is selectable for the desired use and is not intended to be limited. A thin or thick gel can be used. The penetration size given by the pentometer for the non-adhesive gel would range from 150 to 425. The gel can be introduced into the sheath or housing before use or during use.

Depending on the ingredients of the gel, the repair process can take as short as a few minutes to 2-3 hours to insulate the conductor so that a connection is made. Water absorption often begins to occur immediately. A fast-acting composition is typically preferred.

Re-entry into a joint jacket filled with epoxy and urethane resins previously used in the art is difficult, if at all possible. The non-adhesive gel of the present invention can be removed from the joints by hand to make repairs. The gel can be reused instead of being discarded, as was previously required with known epoxy and urethane encapsulants.

The gel containing the adhesive is sticky and intended for use during cable manufacturing. The cable infill composition of the present invention provides a physical barrier to the gel as well as the protection provided by incorporating a polymer into the composition that corrects any short circuits that may occur during use.

Embodiments of the invention are described in more detail below.

The water-absorbent polymer contains a carbon-30 hydrogen chain as a backbone and free anionic groups attached to the hydrocarbon chain. The anionic groups can be carboxylate, sulfate, phosphate, or sulfonate groups, or any other anionic groups that form a negative charge when exposed to water. 35 The salt form of the polymer can be used with a variety of ions 7,96319, including alkali metal ions such as lithium, sodium and potassium, and alkaline earth metal ions such as magnesium, calcium, strontium and barium, zinc and aluminum, but not limited to these. The salt used is determined by the valence of the anionic group attached to the hydrocarbon polymer. Preferred hydrocarbon polymers are particularly well water-absorbing polymers of acrylates, acrylamides, methacrylate, methacrylamide, acrylonitrile, methacrylonitrile, tri- and / or tetraethylene glycol, diacrylate, cellulose, cellulose derivatives and polypropylene derivatives.

The conductors acting as anodes are typically copper. However, conductors made of other anode materials, such as aluminum, nickel, cobalt, chromium, or iron, can also act as an anode at low voltages, as is necessary for transmission in telephone communications.

By nature, such polymers are typically solid. Polymers have been used to spray joints or cables that require drying throughout. A protective, insulating agent is needed inside the diapers to prevent the harmful effects of penetrating water. Dry granules would not easily make contact with water-exposed joints. Geelimat-25 rice provides a dispersant for contacting the polymer with the joints.

The water-absorbent polymer can be dispersed in many different types of gel matrices, and a gel containing a hydrocarbon can be injected into the shell surrounding the joints. A gel containing a dispersed polymer can be used in a limited range, allowing contact to be made between the gel and the conductors or junctions.

Many compositions that are gels or thickenable into a gel are useful. The gel matrix 8 96319 must be somewhat non-conductive with respect to a small direct current. The matrix should provide a fairly uniform dispersion of the anionic hydrocarbon polymer in the gel. The viscosity of the gel can be varied depending on the method used to introduce the composition into the restricted system and the temperature and other conditions in which the composition is used.

Hydrophobic gels tend to coat the polymer and mainly separate it from the conductor in need of protection. A small amount of a hydrophilic substance can be added to the hydrophobic gel. The gel is a polymer carrier. Hydrophilic substances form a channel between the polymer and moisture.

Gels used in this invention include silicones, petroleum gels, high viscosity esters, glycols, polyglycols, olefins and hydrofluorocarbons. Thickening agents can be used with some compounds to achieve the desired viscosity. Typical thickeners for gels and fats include pyrogenic silica, organophilic clays such as bentonite and hectorite, soaps such as metal stearates, and ureas.

In addition, some of the corrosion inhibitors typically used in greases were not found to have any effect on the water absorption or secretion properties of the polymer gel. Anti-corrosion agents must be chosen carefully, as the acid may nullify the effect of the polymer. Neutral barium dinonyl naphthalene sulfonate did not adversely affect the properties of this invention. It had a slight tendency to degrade the gel in one of the gel-30 compositions. The copper passivating agent, a liquid copper triazole derivative, was used without any adverse effects.

If desired, the gel matrix can also be used stained with a color. The amount of toner depends on the depth of the color applied. A small amount of green

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9,96319 dyes were used satisfactorily to stain the gel matrix.

The following are examples of combinations of gels and thickening compositions useful with a water-absorbent polymer containing anionic groups. The polymer used may be any of the polymers described above, including in particular sodium 2-propenoate and salts of a starch graft copolymer of polyacrylic acid and polyacrylamide. The examples illustrate in detail embodiments of the invention.

Example 1

A flowable mixture is prepared using 20 parts by weight of polyisobutene, 4 1/2 parts by weight of polyalphaolefin and 1 part by weight of polyalkylene glycol. The polyalkylene glycol-15 is a random copolymer having an ethylene oxide substitution of 75% and a propylene oxide substitution of 25% and an average molecular weight of 12,000 to 15,000 and a hydroxyl number of 5 to 10 KOH / g. Polyisobutylene has a viscosity (ASTM D-445, 38 ° C) of 210 to 227 and a viscosity number of 20 (ASTM D-567) of 95 and a molecular weight of 750 to about 1,200. The polyalphaolefin used was a long chain polyalphaolefin manufactured by Mobil. SHF-61 having a viscosity (ASTM D-445, 38 ° C) of 30.5 and a viscosity number (ASTM D-2270) of 132. Useful polyalphaolefins, exemplified by Mobil's SHF-61, are typically hydrocarbons. having a molecular weight of 200 to 800. The product SHF-61 is a 1-decene oligomer. The polyalphaolefins have a satisfactory viscosity range of 2 to 100 mm 2 / s (2 to 100 cSt) at 100 ° C.

12 parts of the fluid mixture were mixed with one part of fumed silica to give a gel matrix. The insulation constant of the gel matrix is less than 3. The absorbent hydrocarbon polymer, sodium 2-polypropenoate, is mixed with the resulting gel matrix in an amount of 10% by weight of the final mixture.

10 96319

A 12 V battery was attached to the connected wiring harness and water was introduced into the junction area, causing a short circuit. The bonding area was then filled with the composition of Example 1 and water began to be absorbed within 15 seconds. The short circuit was repaired and the cable pair became conductive.

Example 2

The composition of Example 1 can be used to increase the weight percentage of polyalkylene glycol from 1% to 10%. Example 1 was repeated using polyalkylene glycol at a concentration of 4% by weight of the gel matrix composition. The composition containing 4% polyalkylene glycol functioned most substantially as described in Example 1.

15 Example 3

The gel matrix components of Example 1 were mixed in the same proportions. The polymer, more specifically sodium 2-polypropenoate, is added to the gel matrix in a proportion of 20% by weight of the finished mixture.

It has been found that sodium 2-polypropenoate can be used in conjunction with a gel matrix in the range of at least 10% to at least 33% with satisfactory performance.

Example 4 • The gel matrix of Example 1 was prepared by replacing the polyalkylene glycol with isopropanol. This replacement meant replacing the polyalkylene glycol with another hydrophilic substance.

Isopropanol accounted for 5% by weight of the gel. The gel-30 matrix was mixed in a 2: 1 ratio with the 2-polypropenoate polymer. The reaction time to onset of water absorption was very short; water absorption began in 10 seconds.

Example 5

The preparation of the gel matrix 35 of Example 1 was repeated, replacing the polyalkylene glycol component with 2-ethyl

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11,96319 with hexanol. The proportion of 2-ethylhexanol in the gel matrix was 5% by weight. The gel matrix was mixed with the polymer in a ratio of 2: 1. Water absorption was slower; however, the short circuit was corrected after 20 minutes.

5 Example 6

In the same manner, the gel matrix described in Example 1 was prepared by replacing the described polyalkylene glycol with ethylene glycol. The proportion of ethylene glycol in the gel matrix was 5% by weight. The gel was mixed with a polymer of 10 to 33% by weight. The reaction time was longer; water absorption began after one minute.

Example 7

A gel matrix was prepared as described in Example 1, replacing the described polyalkylene glycol with 5% to 15% hexylene glycol. The gel was mixed with 33% by weight of polymer. Water absorption began immediately and conductivity was restored in about 20 minutes.

Example 8

A gel matrix is prepared as described in Example 1 using 5% by weight of polypropylene having terminal hydroxyl groups and a molecular weight of about 900 as a substitute. The gel was mixed with a polymer of 33% by weight. Water absorption began immediately.

Example 9 A gel matrix was prepared according to Example 1 using instead of polyalkylene glycol a polyglycol consisting of a 50:50 mixture of ethylene oxide and propylene oxide-substituted polyglycol in a proportion of 5% by weight of the gel matrix. The composition of this example began to absorb water immediately when 33% by weight of water-absorbent polymer was mixed into the gel matrix.

Example 10 In this example, a gel formulation is prepared according to Example 1, replacing the polyalkylene glycol with oleic acid, which accounts for 5% by weight of the oleic acid in the gel composition. The gel was then mixed with the water-absorbent polymer described herein, which is used at 33% by weight. The onset of water absorption takes longer when the oleic acid composition is used. In the experiment described in Example 1, power was restored after 40 minutes.

Example 11 In this example, a gel formulation according to Example 1 is prepared by replacing polyalkylene glycol with tall oil-10 fatty acid. The share of tall oil fatty acid in the gel matrix is 5% by weight. The gel is then mixed with the water-absorbent polymer described herein in an amount of 33% by weight.

the effects of oleic acid and tall oil fatty acid were compared to a composition in which the gel did not contain a hydrophilic-15 component. A gel matrix according to Example 1 was prepared without a polyalkylene component. oleic acid and tall oil fatty acid slightly reduce, by about half, the reaction time to the onset of absorption. Without the hydro-additive, it takes at least two minutes before the compound begins to absorb water.

Example 12

A gel matrix was prepared using surfactants instead of polyalkylene glycol. The surfactants used were SPAN® 80 and TWEEN® 80, which are polyoxy-1,2-ethanediyl derivatives of sorbitan mono-9-octadecanoate. Substitute surfactants were used in 5% by weight of the gel matrix. Surfactants altered the consistency of the gel to some extent. SPAN® 80 initially prevented water suction. TWEEN® 80 did not do this and the gel matrix to which the polymer had been added began to absorb water immediately.

Example 13 Another surfactant was used instead of the polyalkylene glycol used in Example 1. This surfactant was 2,4,7,9-tetramethyl-5-decyne-II.

13,96319 4,7-diol. This surfactant accounted for 5% by weight of the gel material. The gel matrix was then blended with 33% by weight of the hydrocarbon polymer to give the final composition. The finished mixture had good water absorption properties. The same surfactant was used to replace 1% by weight of the polyalkylene glycol in the gel. Reducing the amount of surfactant increased the reaction time to the onset of water uptake from the immediate onset to 10 to 20 seconds.

10 Example 14

The polyalkylene glycol moiety of the gel matrix of Example 1 was replaced with 2-polypropylene oxide polyethers of different molecular weights. The two polyethers used had average molecular weights of 1,000 and 2,000, respectively. They were used instead of polyalkylene glycol in a 5% by weight gel matrix. Absorption of water began almost immediately for the lower molecular weight compound and slightly more slowly for the higher molecular weight compound.

20 Example 15

In addition to the gel matrix components described in Example 1, other types of gelling agents were used. 33% by weight of a hydrocarbon polymer was mixed with the polydimethylsiloxanes of the silicone group having a molecular weight of 2,000 to 10,000. Silicones slow down water absorption and insulating effects. When testing the silicone mixed with the polymer, it took hours rather than minutes to repair the shorted wire pair. Silicones could be used in cases where immediate repair is not necessary.

Example 16

The water-absorbing hydrocarbon polymer can be blended with polyalkylene glycols containing a thickener such as fumed silica. The molecular weight range can range from 100 to 90,000 and the alkyl substituents can range from 14,963,319. The hydrocarbon polymer may be added in a proportion of 10% to at least 33%. The viscosity after the addition of the thickener should preferably be 100 to 90,000 mm 2 / s (100 to 90,000 cSt) at 40 ° C.

5 Example 17

The hydrocarbon polymer can be blended into a gel made of paraffin aliphatic, naphthenic or mixed petroleum hydrocarbons. The average molecular weight is 200 to 1,000 and the viscosity is 5 to 500 mm 2 / s (5 to 10,500 cSt) at 40 ° C. Petroleum hydrocarbons shall not contain impurities that corrode the wires in the joints.

Example 18

Fluorocarbon gels have also been used as gel matrices mixed with polymer 15. NYE fluoroether fat 3834, a fully fluorinated fat, was used as the gel matrix. The viscosity of the fluoroether fat is 26 mm2 / s (cSt) at 99 ° C and 270 mm2 / s (270 cSt) at 38 ° C. 7 g of NYE fluoroether, 3 g of sodium 2-polypropenoate and 0.5 g of fumed silica were mixed as a thickener. Water absorption and short-circuit repair occurred slowly but efficiently.

Example 19 9.5 g of the fluorocarbon rice described in Example 18 and the polymer were mixed with 0.5 g of the polyalkylene glycol described in Example 1. The addition of polyalkylene glycol to the fluorocarbon gel matrix resulted in immediate water absorption and correspondingly faster short circuit repair. 1

Claims (15)

A composition for protecting the trees in telecommunications or other cables which lead to low direct current, from damage caused by moisture contact with fault or breakage in their insulation, comprising a dielectric gel matrix, characterized in that a polymer comprising a hydrocarbon skeleton having anionic groups attached thereto is dispersed in the gel matrix, wherein the polymer with the anionic groups, when operated for direct current from a damaged tree, is attracted to the trees to cause an insulation to develop which excludes water from the surface of the tree. and wherein the composition is relatively non-conductive for a low direct current. 2. Composition according to claim 1, characterized in that the anionic groups in the polymer are carboxylate, sulfate, phosphate or sulfonate groups or salts or mixtures thereof. 3. A composition according to claim 1 or 2, characterized in that the polymer is a polymer of acrylates, methacrylate, diacrylate or polypropylene or a site of a starch graft polymer of polyacrylic acid and polyacrylamide. A composition according to any of the preceding claims, characterized in that the gel matrix further comprises a tackifier. Composition according to any of the preceding patents, characterized in that the gel matrix is a silicone, an olefin, a high viscosity ester, a fluorocarbon, a petroleum hydrocarbon, a glycol, a polyglycol or a mixture. thereof. Composition according to claim 5, characterized in that it further comprises a thickening agent. 35 7 ♦ Composition according to any of the preceding patent claims, characterized in that it also comprises a hydrophilic substance. 96319 8. A composition according to claim 7, characterized in that the hydrophilic substance is a glycol, a substituted glycol, a surfactant, a fatty acid, a polypropylene with terminating hydroxyl groups, a polyether or a mixture thereof. Composition according to any of the preceding patent claims, characterized in that the viscosity of the gel is from 2 cSt at 100 ° C to 90,000 cSt at 40 ° C. 10. A method of preventing or repairing a short circuit in trees in a telecommunication cable or cable which conducts weak direct current caused by moisture contact with fault or breakage in its insulation, characterized in that a composition according to any of the claims. claims 1-9 are applied to the cable trees. 11. A composition according to any of claims 1-9, characterized in that it includes a corrosion or rust inhibitor. 12. A composition according to any of claims 1-9 when used within a housing or closure surrounding the trees in a low-power telecommunication cable or cable. The use of a composition according to any one of claims 1-9 within a casing or closure surrounding the trees in a low-current telecommunication cable or cable. 14. A method for manufacturing a low-current telecommunication cable or cable, characterized in that a composition according to any one of claims 1-9 is injected into a casing or closure surrounding the trees of the cable during the manufacture of the cable. Telecommunication cable or cable for weak DC-containing trees, characterized in that the trees are surrounded by a composition according to any of claims 1-9. TL